Akermanite

Formula : Ca2MgSi2O7

Family: 
Melilite
Space group: 
Tetragonal - Scalenohedral H-M Symbol (4 2m) Space Group: P 421m
Dana class: 
55.4.1.1 (55) Sorosilicate Si2O7 Groups, Generally with No Additional Anions (55.4) with cations in [8] and lower coordination(55.4.1) Melilite group
High temperature: 
High temperature mineral.
Geological context: 
A product of contact metamorphism of siliceous limestones and dolostones, and in rocks of the sanidinite facies. Also, forms from alkalic magmas rich in calcium and during smelting processes.

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
 V°
cm3·mol-1
 ΔGºf
J·mol-1
 ΔHºf
J·mol-1
 Sº
J·mol-1·k-1
 CP
J·mol-1·K-1
272.628 92.810 (Ref.: 78hel/del,92ajoh) -3679251 (Ref.: 78hel/del,92ajoh) -3876679 (Ref.: Internal calculation) 209.326 (Ref.: 78hel/del,92ajoh) 211.98 (Ref.: 78hel/del,92ajoh)
CP(T) = a + b·T + ·c·T-2 (T in Kelvin)
a
J·mol-1·K-1
 b * 103
J·mol-1·K-2
 c * 10-5
J·K·mol-1
 Maier Kelley Ref.
251.42 47.70 -47.70 (Ref.: 78hel/del,92ajoh)
Reaction properties

Akermanite + 6H+ + H2O ⇌ 2Ca+2 + Mg+2 + 2H4SiO4

298.15 K, 1 bar log10K: 46.09 ΔH°r:-308213 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 50.96 46.09 40.38 35.12 29.93 25.78 22.28 19.15
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1669.524399 -0.233512 112079.987658 596.354524 -5895295.695317